# Tag Info

39

In our solar system, it is possible for one planet to partially eclipse the sun, but it is not possible for any planet to cause a full solar eclipse as seen from another planet. The sun is too big and the planets are too small and too far apart. Transits occur, and can occur for any pair of planets, but they are very rare. As seen from earth, Mercury only ...

35

As @Donald.McLean said in comments, the answer is yes, the Moon can and does occult the other planets in the Solar System. When something apparently big (like the Moon) passes in front of something apparently small (another planet) it's called an occultation. (I say apparently because from our perspective the Moon appears larger than the planets.) The ...

22

The short answer is no. The alignment occurs, but the eclipse does not, due to the distances and size differences involved. There are a few things to consider here. You already mentioned a lot of them, I'll address those considerations separately. Alignment are alignements of the Sun and two planets actually possible (and if so, how frequent)? We can ...

19

Every Galilean moon and inner moon go into lunar eclipse once per orbit. How often is there a lunar eclipse of the Jovian moons? I set up a little animation of the Galilean moons (I didn't include the inner moons), and made a few assumptions (negligible moon size, sun at infinity, perfectly circular orbits) and found that there is a lunar eclipse in the ...

16

Perhaps this isn't the case for every scenario, but I can think of at least two instances where this can be determined: Stars In the case of stars, it's pretty straightforward to get the spectra of the objects and compare them. If they are identical, with maybe some gravitational redshift, then they're the same object. Galaxies For galaxies, the same kind of ...

15

The orbits of the Galilean satellites have a roughly 2° incline. Based on their distance from Jupiter and on the radius of Jupiter, I computed the apparent diameter of Jupiter from these satellites. The apparent diameter of Jupiter from each of these satellites is 19°, 12°, 7.5° and 4.3° for Io, Europa, Ganymede and Callisto respectively. Therefore, the ...

13

Yes, such events are called occultations. The Moon can occult anything within about 5 degrees of the ecliptic. The visibility of any lunar occultation is limited to a path as wide as the Moon is. This EarthSky article discusses a series of lunar occultations of planets in September 2017, including Venus as seen from Australia. The article includes a photo ...

5

Mutual eclipses and occulations of Jupiter's moons occur during Jovian Equinox, twice in each orbit of Jupiter, and so roughly every 6 years. The last series of events was in 2015, so the next will start in 2021. There will be a series of events between January and August. The site http://lnfm1.sai.msu.ru/neb/nss/nsszph517he.htm can generate ephemerides ...

4

Let’s start with an easy example and say the orbit of the planet with radius $r_p$ around the sun with radius $r_s$ is circular, the orbit of the moon around the planet is circular, the inclination of the moon's orbit is 90 degrees from the planet's orbital plane, and the orbital period of the moon is 1/360th the orbital period of the planet. Let's call the ...

4

The answer can be found in the "Methods" section of the original Nature paper (Stefano et. al). I will try to give a brief sketch of what they did: First thing is, that the eclipsing object is not much larger that that of the emitting source. Only about 0.74 vs 0.43 Jupiter radii. This means you have not just an eclipsed point source, but two ...

4

If you go to the original article, you can see that it's something like this They have a plausible size for the X-ray-emitting source (that is, the X-ray-bright part of the accretion disk): $R = 2.5 \times 10^{9}$ cm, which is about 4 times the size of the Earth. (I think this comes from fitting the X-ray broadband spectrum before and after the putative ...

4

A smoking gun is to show that the two pathways exhibit quantum interference. I don't know if this has been done successfully on astronomical targets yet, but I recall hearing about how ultra-fast radio detectors can enable this trick. By measuring a very short period of time, you can tap into the Time vs Energy duality and get an interference pattern even ...

4

What you describe is a mutual planetary occultation (or transit), and yes, it has happened—in 1737—and will happen again—in 2133 (both dates are for Venus/Mercury events; there are other possible instances of planets passing in front of each other; for example, in 2065, Venus will pass in front of Jupiter). I would suggest giving a look at https://en....

4

@JamesK nailed it, I'll just add a little more. Starting from the link in that answer, I've found the figures below on this page. It looks like this cycle will be difficult to watch in the first months of 2021, until Jupiter moves far enough away from the Sun as seen from Earth. Also, the southern declination will make it more difficult to watch from the ...

3

The angle between the inner and outer edges of the penumbra is the same as the Sun's apparent angular diameter. At 1.0 au from the Sun, that's 32 arcmin or 0.0093 radian. At the distance from the Moon to EM-L2, this angle spans 0.0093 * 64700 km = 602 km. The Moon's diameter is 3474 km, so the umbra diameter would be 2872 km and the penumbra diameter would ...

3

I agree with James K's answer, but just to play devil's advocate. Earth is much too small to cause what we think of as an eclipse when viewed from Mars or Jupiter. But in a sense, a transit is like an annular eclipse. Nobody would ever call a transit an annular eclipse, because it sounds stupid, but it's kind of the same thing. Phobos is smaller than ...

3

No. There are two types of eclipse: A lunar eclipse is when the moon goes into the Earth's shadow. We can see a lunar eclipse because the moon is so close to the Earth. If you were standing on the moon, The Earth would look bigger in the sky than the sun. If the Sun, Earth and moon are aligned, the Earth will block out the light from the sun. Mars and ...

3

Since the Earth is approximately 109 times smaller than the Sun (regarding radius), and the distance between them is about 150 million km, the eclipse will be visible up to about 1.39 million km from the Earth. This distance will vary (1.36 - 1.41 mln km) because the distance Earth-Sun varies during the year. This is about 3.6 times more than the Moon-Earth ...

3

First, the Moon is not a planet and therefore not applicable to this question. Second, the inferior planets, specifically Mercury and Venus cannot have a shadow cast by the Earth because their orbits are inside those of Earth. Notice I did not say they are between the Sun and the Earth, as they could be in superior conjunction with the Earth (opposite side ...

3

It would be dark. Titan in eclipse can be dimly lit by refracted sunlight and light scattered by Saturn's rings. The refracted light would be reddened, but the scattered light would be white. But there isn't much light that far out, and so the brightness would be very low. It has been imaged in eclipse: See https://solarsystem.nasa.gov/resources/14528/...

2

About Mars moons, eclipses and transits (from NASA - Curiosity Captured Two Solar Eclipses on Mars: Phobos doesn't completely cover the Sun, so it would be considered an annular eclipse. Because Deimos is so small compared to the disk of the Sun, scientists would say it's transiting the Sun. Phobos does pass in front of Deimos but the current models of ...

2

The short answer is no, septuple eclipses can’t happen. Using a method described by Meeus in Mathematical Astronomy Morsels (p. 190), we find that while it is, in theory, possible, for the seven satellites to align, it happens only once per ~ 20 million years—and that’s among themselves only; I didn’t factor in the Sun’s position yet! The possibility that ...

2

tl;dr: Is it ever possible to see Earth's shadow on other planets?" No but this is really interesting because the answer to Is there any way of using such a phenomenon to help prove that the Earth is a spheroid? is Yes Maybe! We couldn't actually "see the shadow" as explained in other answers. Seen from the outer planets Earth would be transiting ...

2

This is basically a repeat of Aristarchus’ experiment of trying to figure out the distance between the Earth and the Moon from a lunar eclipse. See for example https://pwg.gsfc.nasa.gov/stargaze/Shipprc2.htm So, we know that Iapetus orbits Saturn in 79.3215 days, at an average distance of 3,560,820 km. Saturn’s diameter is 116,464 km, and it orbits the Sun ...

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With a small telescope/binoculars, it will be difficult or impossible to resolve details on the scale of Io's disk (about 1 arcsecond). So you wouldn't be able to use shapes in the image to distinguish the two scenarios. If you can attach a color filter, you might be able to distinguish between transit and occultation. Both Io and Jupiter are yellowish, so a ...

1

Because of the much greater distance from the sun, and the much greater size of Saturn compared to Earth, while there may be a brief period when Titan goes into eclipse where there will still be some refracted sunlight, as well as some reflected light from the rings, for the majority of the eclipse Titan will be effectively dark. And this assumes you have an ...

1

The orbital period of the moon is $$2\pi \sqrt{\frac{911000000^3}{G\times3.8 × 10^{27}}}=343000\text{s}$$ or 95.3 hours. I've found, by drawing, that assuming everything lines up (the moon orbits exactly in the plane of the sun, etc) that for 14/360 degrees of the orbit, the satellite will be in the moon's shadow. I carefully drew the orbits and the shadows ...

1

Most moons orbit in the equatorial planes of the planets they orbit. Earth's moon is a big exception. Because of the varying tilt angles of planets, some satellite systems are too far out out the planes between their planets and their stars, and so never pass into the shadows of their planets and never get eclipsed by their planets. Other planets have ...

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